Project Abstract This proposal describes a 5-year research plan that seeks to address gaps in our understanding of the individual, geographic, and sociocontextual determinants of delays in achieving HIV viral suppression (VS) in the Deep South region of the United States (US), an area carrying a disproportionate burden of the country?s HIV epidemic. The proposal leverages a dynamic and innovative collaboration of experienced investigators from the University of Alabama at Birmingham (UAB) Center for AIDS Research (CFAR) and the HIV Divisions of the state health departments in Alabama (AL), Louisiana (LA), and Mississippi (MS). This novel research proposal utilizes a population-health approach to evaluate time to VS among newly diagnosed individuals and integrates a mixed-methods approach to examine the socioeconomic, demographic, and structural determinants of time to VS in this population in the development of an intervention to accelerate initiation of antiretroviral therapy (ART). The specific aims of this proposal are to: 1) Utilize HIV surveillance data collected by the states? public health electronic HIV/AIDS Reporting System (eHARS) to characterize geographic variability in time from HIV diagnosis to VS (<200 c/mL) among newly reported HIV cases among those age ?13 years at diagnosis between January 2014-December 2017 in AL, LA, and MS; 2) Identify individual and community-level determinants of time to VS, incorporating quantitative geospatial coding methods, in AL, LA, and MS among newly reported cases of HIV among those age ?13 years at diagnosis from January 2014-December 2017 and contextualize these findings with qualitative key informant interviews among persons living with HIV (PLWH), HIV treatment and social services providers, and other community stakeholders in AL, LA, and MS; and 3) Engage stakeholders in developing a rapid ART initiation program focusing upon localities in the Deep South with disproportionately longer time from HIV diagnosis to VS. We will then incorporate these results in an R01 application testing the implementation of a community-level rapid ART initiation program in the Deep South, focusing on areas with longer time from HIV diagnosis to VS. Results of this research will lay the groundwork for a larger implementation trial that will include rigorous evaluation of interventions integrating clinical and public health systems aimed at improving time to VS in the US with consideration for cost-effectiveness.